Figure 1
From: Curvature-driven bubbles or droplets on the spiral surface
Migration of a droplet or bubble on an spiral.
(a) Snapshots of a droplet moving on the concave side (upper row) or convex side (lower row) of the Archimedean spiral made of PMMA. (b) Snapshots of a bubble moving on the concave side (upper row) or convex side (lower row) of the Archimedean spiral made of PMMA. (c) Snapshots of a bubble moving on the concave side (upper row) or convex side (lower row) of the Archimedean spiral made of PE. (d) The velocity of a bubble moving on the concave or convex side of an Archimedean spiral made of PMMA or PE. (e) Snapshots of a droplet deposited on the concave side of the pitcher rim of Nepenthes alata. The droplet spreads and moves towards the position of the logarithmic spiral with highest curvature quickly, with a decreasing volume (marked with blue arrows). In order to remove the effect of the droplet’s gravity, the spiral rim is set horizontal.
